agreed. Also I agree that in two cases the NOC should be given by default. First, when the employee got terminated, he/she has to get the NOC per her/his request. When the employee has completed the initial contract, whether it is 1, 2, 3 or 5 years, doesn't matter. Once the duration of the contract, signed by both parties, is over, employee has to get a NOC as per request.
But if the employee has been brought to Qatar, and just simply "didn't like" it here, or got another offer, couple of bucks more, it shouldn't be a reason for waiving the terms of the contract.